Method for producing a silicon-based timepiece spring

Abstract

A method for producing a timepiece spring includes the following steps: producing a piece based on silicon, having the desired shape of the timepiece spring; thermally oxidising the piece; deoxidising the piece; annealing the piece in a reducing atmosphere; forming a silicon oxide layer on the piece.

The invention claimed is: 
     
       1. Method for producing a timepiece spring, comprising the following steps:
 a) producing a piece based on silicon, having the desired shape of the timepiece spring or comprising a part having the desired shape of the timepiece spring, 
 b) thermally oxidising the piece, 
 c) deoxidising the piece, 
 d) annealing the piece in a reducing atmosphere, 
 e) forming a silicon oxide layer on the piece. 
 
     
     
       2. The method as claimed in  claim 1 , wherein step a) comprises an etching operation. 
     
     
       3. The method as claimed in  claim 1 , wherein the thermal oxidation step is carried out at a temperature between 600° C. and 1300° C. 
     
     
       4. The method as claimed in  claim 1 , wherein the annealing step is carried out at a pressure strictly greater than 50 Torr. 
     
     
       5. The method as claimed in  claim 1 , wherein the annealing step is carried out at a pressure strictly greater than 100 Torr. 
     
     
       6. The method as claimed in  claim 1 , wherein the annealing step is carried out at a pressure lower than or equal to atmospheric pressure. 
     
     
       7. The method as claimed in  claim 1 , wherein the annealing step is carried out at a temperature between 800° C. and 1300° C. 
     
     
       8. The method as claimed in  claim 1 , wherein step e) is carried out by thermal oxidation. 
     
     
       9. The method as claimed in  claim 1 , wherein the silicon is monocrystalline or polycrystalline. 
     
     
       10. The method as claimed in  claim 1 , wherein step a) comprises a deep reactive etching operation. 
     
     
       11. The method as claimed in  claim 1 , wherein the thermal oxidation step is carried out at a temperature between 800° C. and 1200° C. 
     
     
       12. The method as claimed in  claim 1 , wherein the deoxidation step comprises an etching operation, a vapour phase etching operation or a dry etching operation. 
     
     
       13. The method of  claim 12 , wherein the deoxidation step comprises a wet etching operation. 
     
     
       14. The method as claimed in  claim 1 , wherein the timepiece spring is a mainspring, a hammer spring, a lever spring, a rocker spring, a pawl spring, a jumper spring, a hairspring or a flexible guide. 
     
     
       15. The method of  claim 14 , wherein the timepiece spring is a mainspring in the form of a barrel spring. 
     
     
       16. The method as claimed in  claim 1 , wherein said reducing atmosphere includes hydrogen. 
     
     
       17. The method as claimed in  claim 16 , wherein said reducing atmosphere also includes an inert gas. 
     
     
       18. The method of  claim 17 , wherein the inert gas is argon. 
     
     
       19. Method for producing a timepiece spring, comprising the following steps:
 a) producing a piece based on silicon, having the desired shape of the timepiece spring or comprising a part having the desired shape of the timepiece spring, 
 b) annealing the piece in a reducing atmosphere, 
 c) thermally oxidising the piece, 
 d) deoxidising the piece, 
 e) forming a silicon oxide layer on the piece. 
 
     
     
       20. The method as claimed in  claim 19 , wherein step a) comprises an etching operation.